Stir in 1/2 cup sugar, 1 teaspoon salt and 1/2 cup butter. Cool to lukewarm.,In large bowl, sprinkle 2 packages yeast over 1/2 cup lukewarm water.,Add sour cream mixture and 2 beaten eggs. Gradually add 4 cups flour.,______,Cover tightly and refrigerate overnight or at least 8 hours. (I add the first 2 cups of flour with an electric hand mixer, then the last 2 cups by hand.)